The present invention relates to papermaking machines, and more particularly relates to a method and apparatus for achieving a continuous paper winding process using a number of reel-up stations at different locations along a travelling paper web path wherein one station is always prepared to commence winding upon completion of the paper roll at another station.
In the manufacture of various types of tissue products, such as facial tissue, bath tissue, paper towels and the like, the dried tissue web or sheet coming off of the tissue machine is initially wound into a parent roll and temporarily stored for further processing. Sometime thereafter, the parent roll is unwound and the sheet is converted into a final product form.
In a conventional dry end of a papermaking machine, the dried web is wound into rolls by the reel-up. The conventional reel-up includes a rotating reel shaft held by a pair of primary arms against a reeling drum to form a nip. The free end of the continuous paper web, in the form of a leader, is introduced into the nip. The paper web is adhered to the reel shaft by a vacuum tape or glue and winds onto the reel shaft as it is advanced into the nip to form a roll. Once partially wound, the primary arms transfer the roll to a set of secondary arms which complete the winding process. After the roll is completed, the continuous paper web is severed, the downstream portion of the web becoming the tail end that is wound onto the completed roll and the upstream portion becoming the new leader.
Completion of the roll frees the apparatus to receive a new reel shaft. A pair of lowering arms, positioned above the primary arms and the reeling drum, retrieve a new reel shaft from a stock of reel shafts and lower the new reel shaft into the primary arms. The primary arms grippingly receive the new reel shaft and hold the new reel shaft against the reeling drum to form the nip. The new leader is advanced into the nip to begin a new roll.
Reel changing methods are commonly assisted by balloon blowing. Balloon blowing entails creating slack across the full width of the paper by somewhat retarding the finished roll. With the aid of compressed air, the fold thus formed is then forced into the nip between the new reel shaft and the reel drum, after which the paper web is cut off. The degree of control over the paper web in the balloon blowing procedure is relatively low because the web is not supported on any support in the ballooned portion of the web. This lack of control can lead to problems.
U.S. Pat. No. 5,901,918 to Klerelid et al. (""918) addresses this lack of control by providing support for the paper web during reel switching. The apparatus disclosed by the ""918 patent includes a reel-up having a fabric run defined by a flexible transfer belt spanning two support rolls. The flexible transfer belt supports and advances the paper web. The web is transferred from the transfer belt to a parent roll as the parent roll is urged against one portion of the flexible belt. Reel switching occurs when a new reel spool is lowered into an initial winding position against the web on another portion of the belt. No balloon blowing is used and the paper web is continuously supported. However, arms are required to lower the new reel spool into the initial winding position, and the new reel spool must be moved along the transfer belt from the initial winding position into a final winding position as winding proceeds. This movement of the building paper roll complicates the control of the nip load.
Another disadvantage of reel switching is the production down time associated with the reel switching process. The production of large jumbo rolls minimizes the frequency of reel switching. However, jumbo rolls are even more difficult to wind and handle due to their size and weight. The winding process typically starts when a core is brought into contact with a reel drum supporting the paper web. Controlling the linear load in the paper web at the nip during initiation of the winding process is made more difficult by the heavy core shafts of the jumbo rolls. These difficulties continue as the roll is wound and its weight increases, because the tissue paper web is fragile and sensitive to the nip pressure. Conventional reel-ups require a complicated control system to control the linear load and meet requirements for tissue web quality when winding jumbo rolls. Manufacturing losses from these difficulties occur because the failure to control linear load often results in 200 to 300 meters of tissue paper web at the beginning of the jumbo roll not being of commercial quality.
Therefore, it would be advantageous to have a reeling apparatus that always supports the paper web and that minimizes any delay caused by the reel switching process. It would be further advantageous to have a reeling apparatus that produced smaller rolls without additional production down time.
These and other needs are met by the multi-reel apparatus according to the present invention. The present invention avoids problems with web instability by supporting the paper web along its entire path through the apparatus. Delays in parent roll production are reduced by alternating between multiple reeling apparatuses so that any one apparatus is winding paper web onto a parent roll while the others are swapping a completed parent roll for a new empty reel shaft. The reduction in down time due to reel switching allows for the production of small rolls which are easier to wind and handle.
A paper web manufacturing machine includes a wet section having a former for forming a wet web, a drying section for drying the wet web, and the multi-reel apparatus for winding the dried web into completed rolls. The multi-reel apparatus includes a web support which supports the travelling web along a path of travel that extends from a first vertical level to a second vertical level, wherein the two levels are vertically spaced. First and second reeling stations are located, respectively, at the first and second vertical levels. Each reeling station has a reeling device operable to hold and rotatably drive a core onto which the web is wound to form a roll. The reeling devices are further operable to move the core into engagement with the web on the web support thereby initiating winding of the web onto the core. The reeling devices are also operable to move the core away from the web support when the roll is fully wound so that the web can begin winding onto the core held in the reeling device of the other reeling station. In this manner, the web is continuously wound alternately in one reeling station and then in the other reeling station. This increases the efficiency of the papermaking process by eliminating the down-time during reel switching.
In another embodiment, the continuous web prior to winding is divided into two partial-width web portions. Each reeling station includes two reeling devices spaced in the width direction of the web for the simultaneous winding of the two web portions. The continuous web is alternately wound in the two reeling devices of the first reeling station and then in the second reeling station. The partial-width web portions are advantageously wound onto separate cores and shafts at each station to form small rolls that are easily manipulated in additional downstream processing. The small rolls generally have lighter cores and shafts, and can even use composite based shaftless cores for an additional reduction in weight and an increase in reeling speed.
In yet another embodiment, the partial-width web portions are simultaneously wound in the first and second reeling stations into small rolls. Each reeling station includes first and second reeling devices that are vertically stacked whereby each web portion is continuously wound alternately in the first and then the second reeling devices of each reeling station.
Initiation of a new roll preferably is aided by a cutting device operable to sever the web when the roll in one of the reeling stations is completed so that the other reeling station can begin to wind the web onto its core. The cutting device may be combined with an adhesive applicator positioned adjacent to the path of travel of the web and upstream of the reeling stations. A signal triggers the adhesive applicator to apply adhesive to the web and the cutting device cuts the web so that the cut is downstream of the applied adhesive.
The web support in some embodiments comprises an endless carrying clothing guided along the path of travel by a plurality of rolls about which the clothing is looped. This clothing may be a through-air drying fabric on which the web is dried in the drying section, or it may be a separate clothing that receives the web from the drying section. Alternatively, the web support may comprise a foil or plurality of foils for supporting the web thereon.
The multi-reel apparatus has several advantages. The elimination of down time for reel switching allows for continuous paper web production and the cost-effective production of small rolls in place of jumbo rolls. Small, relatively light rolls reduce winding and downstream handling problems associated with heavy jumbo rolls. Lighter reel shafts used in smaller rolls are more easily controlled by the reeling device to maintain proper web tension and nip load for high quality tissue paper web production. In addition, the multi-reel apparatus does not require lowering arms or any mechanisms for moving a new reel shaft on which winding is commencing from an initial winding position into a final winding position previously occupied by the prior-wound roll. This further improves the simplicity of operation as well as the control of the nip load.